MICA and MICB overexpression in oral squamous cell carcinoma

Background: The concentration of MICA in serum seems be a good candidate marker in cancer. Previous studies from our laboratory have shown that the polymorphic MIC gene may confer a risk for oral squamous cell carcinoma (OSCC). The study investigated the expression levels of MICA and MICB of OSCC patients and cancer cell lines. Material and methods: We used RT‐PCR to analyze the mRNA expression of MICA and MICB in four oral cancer cell lines compared with three normal human oral keratinocyte (NHOK) cell lines and in tissues from 36 patients with OSCC comparing tumor tissue with non‐cancerous matched tissue (NCMT). Results: Endogenous MICB mRNA expression in OSCC cell lines was significantly higher than that in NHOK (1.40 ± 0.27 vs. 0.40 ± 0.16; P = 0.04). In 20 of 36 sets of tissue from patients with OSCC, MICB mRNA expression was higher in the cancerous tissue than in the NCMT. The mean MICB mRNA expression in OSCC tissues was significantly higher than in NCMT (0.39 ± 0.08 vs. 0.14 ± 0.03, P = 0.009, paired t‐test). A significantly lower MICA mRNA was found in patients who chewed areca nut compared with those who did not use areca (P = 0.001) and in patients with well‐differentiated tumors compared with those with less well‐differentiated tumors (P = 0.02). Conclusion: MICA and MICB mRNA expression may be increased in OSCC but there appears to be individual variation.